Phototypographical machine



1960 w. s. GORRILL PHOTOTYPOGRAPl-{ICAL MACHINE 5 Sheets-Sheet 1 FiledNov. 14, 1957 INVENTOR WILLIAM STERLING GORRILL ATTORNE Feb. 2, 1960 w.s. GORRILL 2,923,214

PHOTOTYPOGRAPHICAL MACHINE Filed Nov. 14, 1957 5 Sheets-Sheet 2 a w w.WMJ. a. M, WMMHHMHHHNWHH..HH.HH....M:M w HM W P w INVEVTOR. WILLIAMSTERLING GORRILL I 47mins ll'l LIIIIII Feb. 2, 1960 w. s. GORRILLPHOTOTYPOGRAPHICAL MACHINE 5 Sheets-Sheet 3 Filed Nov. 14, 1957 INVENTORL L m w E Gym mwm R m A 8 u n w Feb. 2, 1960 w, 5, GORRILL 2,923,214

PHOTOTYPOGRAPHICAL MACHINE Filed Nov. 14, 1957 5 Sheets-Sheet 4 INVENTORWILLIAM STERLING GoR L M w TTO EY Feb. 2, 1960 w. s. GORRILLPHOTOTYPOGRAPHICAL MACHINE 5 Sheets- Sheet 5 Filed Nov. 14, 1957 tux-E aINVENTOR 1 WILLIAM STERLING GORRILL ATTORNEYS 2,923,214PHOTOTYPOGRAPHICAL MACHINE William Sterling Gorrill, Glen Head, N.assignor to Mergenthaler Linotype Company, a corporation of New YorkApplication November 14,1957, Serial No. 696,446 8 Claims. ((11. 95-45)film or paper for line composition as a relative movement takes placebetween the sensitized film or paper and the position to which characterimages are projected.

in a machine of the type therein'disclosed, a font plate having an arrayof transparent characters which vary in set widths on a unit basis isinterposed between a source of light and a shutter mechanism whichserves to selectively expose the various characters. In operation, the

shutter mechanism is actuated to expose a character selected to bephotographed and thelight source is then rendered operative to projectlight through the character to a lenslet individual to the character.The lenslet forms the light which passes therethrough into a bundle ofcollimated rays and these impinge on an imaging lens common to all thelenslets. The imaging lens, in turn, serves to form, in space and on itsoptical axis, an image of the United States Patent selected character.vA point size changing lens system is provided comprising two eye piecelenses whose combined function is to vary the size or magnification ofthe selected character as it is finally recorded on thesensitized filmor paper. The eye piece lenses also serve to transmit the light formingthe image in space as a bundle of collimated light rays to a mirrorcarried by a carriage that continuously traverses the sensitized filmduring the composition of a line, the film remaining stationary duringcomposition. The mirror deflects the bundle oflight rays at an angle of90 and directs it to a further lens system which is also mounted on themoving carriage and which serves to decollimate the light rays andproject them onto the stationary light sensitive film to form an imageof the selected character in apoint size controlled by the setting ofthe eye piece lenses.

The operation of the machine is controlled by means of a coded tape.,Each character to be photographed is rep resented on the tape by a codesignal which may be thought of as comprising two portions, none of whichidentifies the character and controls the operation of the shuttermechanism to selectively expose the character to be photographed, andthe other portion of which represents the unit set width of thecharacter and is transmitted to an electronic counter. An opaque gratingor grid plate, having a row of translucent slits spaced apartin units ofan em of the point size of the photographed characters, is secured tothe carriage for movement therewith and traverses a light beam extendingfrom a light source to a photocell in such a manner as to transmit thelight beam to the photocell for each unit of an em travelled by thecarriage. The resulting pulses from the photocell are transmitted to theelectronic counter. When the number of pulses from the photocellcorrespond with the numerical value of the unit width of the charactertransmitted to the counter by the code signal on the tape, the

twelve point composition,

2,923,214 Patented Feb. 2, 1960 r ce It is to the grating grid platethat the present invention is particularly directed.

Inasmuch as the pulses generated by the movement of the grating past thelight beam of the photocell unit control or determine the position onthe sensitized film or paper at which the selected characters areimaged, it will be appreciated that the grating must be manufacturedwith great precision. If we consider a twelve point typographical em, wefind that the em square has a width (and height) of one sixth 45) of aninch. Furthermore, if we consider an eighteen unit system wherein thetypographical cm is divided into eighteen subdivisions or units, we findthat one unit equals a width of approximately ninethousandths (0.009) ofan inch. it, therefore, is quite obvious that the miscount of even oneunit will'cause the displacement of the image of a selected characterformed on the film or paper by an amount which could not be tolerated infine typography.

Furthermore, there are various. conditions unavoidably encountered inthe normal operation of a phototypographical machine which would lead tothe miscounting of pulses from the photocell unit. Only one will bedescribed by way of illustration. When it is desired to change the typeface in a line of composition, as by italicizing certain words, it isrequired that the font plate be changed and a new one bearing charactersof the desired face be brought to photographic position. Since it .takessome time to effect the substitution of one character font plate foranother, the continuous movement of the projection lens carriage whichcarries the grating is arrested and the carriage brought to a halt.After the change of font plates is completed, the line composingmovement of the carriage is reinaugurated.

In arresting the carriage movement, the carriage must be brought fromline composing speed to zero speed before it traverses a distance equalto the width of the narrowest possible character. Since this may be afour unit character, the carriage must be brought to rest before ittravels approximately the four units or in the case of thirty-seventhousandths (0.037) of an inch. This situation is aggravated for smallerpoint size characters, since the distance is proportionately smaller. Inorder to stop the carriage in such a short distance, resort is had tothe provision of a strong 'vibration of the carriage will causethe lightbeam to be repeatedly interrupted with theresult that av fictitiouscount is introduced to the counter. This, of course, will lead to thecharacter next to be imaged being improperly positioned on thesensitized film or paper. it is to obviate this difficulty that theapparatus of the present invention is provided.

In carrying out the invention, there is provided an opaque gratinghaving a series of successively acting translucent slits disposed in twoadjacentrows, those ,of one row being spaced apart so that the distancefrom the boundary between the opaque background and the translucent areaof a slit is two units of an em from a corresponding point of the nextadjacent slit in the same row, and a second row of translucent slitssimilarly spaced apart but disposed relative to the first row of. slitssuch that the distance from the boundary between the .opaque backgroundand the, translucent area .ofa slit. in. o'ne row .is one unit of anemfrom a corresponding point of i the next adjacent slit in the otherrow. In this manner, as the grating is carried past the light beam ofthe photocell..unit, the light beam isinterrupted and restored by theslits of the two rows alternately. Circuitry is proferred embodimentthereof which follows.

In the drawings: -Fig. l is a-front elevational-view of a photocomposing'machinegembodying a grating according to the present invention;

. Fig. 2 is a front -elevational view of the grating;

sensitized ,filrn 135 provided If a succession of pulses is gen- Fig. 3is an enlarged sectional view taken along line 3-3 of :Fig. 2;

Fig. 4 is a top plan (edge) view of the grating; Fig. 15 is an enlarged'fragmental view showing the translucent slit arrangement of thegrating;

Fig. 6 is a side elevational view, partly in section, showing therelationship of the grating to the photocell unit;

Fig. 7 is a view taken along line 77 of Fig. 6;

Fig.8 is a fragmental sectional view taken along line Fig. 9 is anelevational view' looking into the light source tube and showing themeans'for forming the light beam into a narrow band; 1

Fig. 10 is a top plan view showing the relationship of the grating tothe photocell unit; and

Figs. 11 and 12 are schematic block diagrams showing .source. The lightis then distributed relatively evenly over the area of a .font plate 123.by a condensing lens system 124, the font plate having an entire array.of transparent characters arranged thereon against an opaque background.The set widths of the several characters vary one from another onaunits-of-an-em basis. That is, the typographical em is divided into afinite number of equal parts ,or units and each character is assigned a'widthof so many units. The present system is based on an eighteen unitem, although it could have been based on an em comprising more or lessunits depending on the degree of typographic. refinementdesired. An

.5 eighteen unit system hasbeen found to be entirely satis factory.

A shutter mechanism 125 is nextprovided whereby .the

light-passing through asingle character selected for reproduction willbe transmitted to succeeding machine --jcomponents. Located forward ofthe shutter mechanism,

within housing 130, is a lenslet array 126 which includes lenslets andthe font plate are disposed relative to each other such that lightpassing through a selected character .is collimated by the associatedlenslet. A single .imaging lens 127, common to allof the lenslets.ofarray 126,. is

providedywithin the housing 130, the lens 127 serving to form an image,in space andon its optical axis, of a selected character. The positionof .the image alongrthe optical axis is determined by the location of aneyepiece objective lens 131. The light transmitted through the lens 131is next 'collimated by a second eyepiece lens in filmmagazin 1 -v Tmirror 133 and lens system 134 are located within a housing 137supported by a carriage 140 which is mounted for reciprocatory motionbefore the sensitized film to effect the character by charactercomposition of a line.

In a machine as herein contemplated, the carriage is driven continuouslyby a reversible motor 141, the drive mechanism being'the spur gear unit142 and lead screw 143 which is threaded into' the follower block 144secured to the underside of the carriage. Since the carriage traversesthe stationary film continuously (rather than in intermittent'steps ofadegree depending on the .width of the photographed characters),there isprovided means for determining at which point of carriage travel acharacter is tobe photographed. Such means include the point sizegrating 19 which depends from one side of the carriage so as to betranslated therewith. The grating, which cooperates with a stationaryphotocell unit in a manner hereinafter to be described, itself includesaplurality of rows of translucent slits equally spaced on an opaquebackground. The leading edge, considering the direction of tlfllVQl ofthe grid plate, of each slit in a selected row is spaced from thecorresponding pointjof the preceding slit by a distance equal to'aunit-of-an-em of the point size ,for which therow is provided. Each rowof slits corresponds to a particular point size; which can bereproduced-in the machine. Thus by way of example, the five rows ofslits illustrated represent the point sizes 5,. 5 /2, 6,1 7, 8 and 9reading from top to bottom, respectively For a means to bring a selectedrow of .slits into cooperative relation with the photocell unit, seecopending application. Serial No. 624,136 filed November 23, 1956. Inoperation, asthe grating traverses the light beam of the photocell unit,the photocell is energized or pulsed by .a beam of light for each unitof :an em travelled by the grid plate and hence the carriage.

-The. point size grating 19, mounted on the projection lens carriage, isshown more in detail in Fig. 2. The grating includes a translucent glassplate 20 with an emulsion coating 21 adhered thereto. 'In' the finalform in which the grating finds utility, the emulsion coating has anopaque background with a series ,ofsuccessively acting translucent-slits22 arranged in rows and-spaced apart such that the leading edge of eachslit is two units-of-an-em of the point size for'whichthe row isprovided from the corresponding position of the next adjacent slit inthe row. Two juxtaposedrows (shown bracketed in Fig; 5) are Suflice itto say that in the identical. However, the slits mom of the rows are displaced longitudinally so that the leading edge-of each slit, whilespaced twoun'its ofan em from thecorresponding-position of an adjacentslitin thesame row, is spaced one unit 1 of an em'from the correspondingposition of nearestslitin the associated row. Therefore, if one conanindividual lenslet for each character of the font. .The

siders a pair of lightbeams traversing the pair of rows of slits,oneb'eam scanning onefr'ow 311 211116 second beam scanning the otherrow,one or the other light beamwill be flashed for each unitof-an-emrelative movement b'e-i tween the grating and 'thelight beams. Ofcourse, the

light beams will be flashed alternately. For the sake of clarity, thetransparent 's'lits are shown as though "they were opaque andthebackground as if it'were transparent. It w'illlbe appreciated thatthe spacing between adjacent slits in eachpair of associated rows willbedependent on the point size of the reproduced character images forvwhich the rows areprovidedand, consequently, the spacing of the slitsforthe smaller point sizes will be less than that for the largerpointsizes. It will be observed that the first slit in the row for asmaller point size offset .tr m, ver ica lineiprsie esl th ugh th fir lt-Qf larger point size. This attribute, which, is more fully disclosedcopending application Serial No. 432,757 filed May 27, l954, insure sthat a contantor even left hand margin is obtainedregardless of thepoint size of the reproduced character images. 1

J, The glass plate 20 is secured within a first frame 23 by cementingthe plate in the shoulder provided, while the frame 23 is, in turn,secured. to frame 24 as by screws 25. Anelongated collar 26, which isslidably disposed on the guide rod 27, is fastened to frame 24 by pins28. By this structure, the grating may be positioned vertically to bringany pair of associated rows of slits into operative alignment with aphotocell unit, as disclosed in aforementioned application Serial No.624,136. A stop member 30, secured to the lower end of guide rod 27,prevents the grating assembly from being inadvertently disassociatedfrom the guide rod. I

Referring to Figs. 6 and 10, it is seen that the grating is interposedbetween a pair of light sources 31 and 32 and a photocellunit comprisinga pair of photo-electric tubes 33 and 34. The first light sourceincludes a lamp 35 mounted in a housing 36 which is supported above themachine bed plate 37 by a bracket 40. Projecting from housing 36 is atubular member 41in which is mounted a simple lens system (not shown)which converges the light beams emitted by lamp 35 so that they maybefocused on the photoelectric tube cathode. .A cylindrical cup-shapedmember 42;(Fig. 8), secured within the tubular member by pin 43, isprovided with an elongated aperture 44. A pair of plates 45 (Fig. 9) aresecured byscrews 46 to the transverse portion of member 42 so that theymay be adjusted toward or away from each other to provide a narrow slitthrough which the light beam passes. It will be observed that theadjacent edges of the plates areprovided with knife-like edges tominimize dispersion of the light beam.

Thesecond light source 32 similarly includes a lamp 50 mounted ina-housing 51 which is supported abovethe machine bed plate by a bracket52. A tubular member 53, projecting from the housing, containsa simplelens system which converges the light beam emitted by lamp 50. Thislatter tubular member also has mounted therein a cup-shaped memberhaving an elongated aperture similar to that provided in member 41 andshown in Figs. 7 and 8,; whereby the width of the light beam can becontrolled.

The two housings 36 and 51 are joined together by a connecting piece54so that a single chamber, in effect, is obtained. A hose 55 is connectedto an inlet port 56 formed in housing 51 while a second hose 57 isconnected to the outlet port 58 formed in housing 36. A current of airis circulated through hose 55 into the connected housings, over thelamps, and out through hose 57. In this manner the heat produced by thetwo lamps is carried away from the mechanism and overheating of thehousings and lamps is prevented;

7, It will be noted that the arrangement of parts is such that the lightbeam from source 32 will intersect the grating at a higher point thanthat at which the light beam from source 31 intersects the gratingthereby assuring-that one light beam will intersect one row of slitswhile the second light beam will intersect the other row of slits in anassociated pair of rows; Furthermore, the beams of light both intersectthe emulsion surface of the grating along a precise vertical line (seeFig. This has been found extremely desirable in order to provide anaccurate measurement of carriage travel. 7

Turning now to a consideration of the photocell unit, this is seen to besimply a pair of photo-electric tubes 33 and 34 supported on a pair. ofangle brackets 60 within box 61. The face of the box is provided with anopening 62 in which is mounted a lens 63. From the top of the box abracket 64 supports the angularly disposed depending mirror 65. Themirror, in conjunction with lens 63, directs the light beam from source31 to the Cathode 66 of photo-electric ,tube33. .The light beam fromsource is refracted by lens 63 to energize th'e c athode 67 ofphotoelectric tube 34. v

Itis believedv apparent from the foregoing description, particularlyofthe alternate arrangement of slits in .an associated pair of rows,that, as the carriage and the grating carried thereby traverses .thelight beams from the pair of light sources, the photo-electric tubeswill be alternately energized and considering the pair of photoelectrictubes as a unit, that a photo-electric tube will be energized for eachunit ofan em travelled by the projection lens carriage and grating.

Referring now to Fig. 11, the photocells 33 and 34, which haveheretofore been shown in mechanical detail, are now illustrated in the.pulse generating circuit 7 for which they are provided. I i

The photocell 34 isconnected in a potentiometer circuit comprisingresistors 70, 71 and 72 which are connected to a 150 volt powersupplyand ground as shown. The junction between the. photocell cathode 67 andgrid .resister 72 is connected to the grid73 of tube 74, the-tubenormally being in an extinguished or non-conducting condition. However,when photocell tube 34 begins to conduct current, as when the cathodethereof is illuminated by the light source 32 as a slit on the grating,as distinguished from the opaque background of'the grating, isinterposed between the light source 32 and the photocell tube 34, avoltage isimposed ongrid 73 causing tube 74 to fire and conduct current,Thereafter when the slit is completely traversed, the photocell tubeceases to com duct and tube 74 is extinguished. Whentube 74 firstconducts and then is extinguished, the voltage at cathode 75 rises fromits quiescent-value to a higher voltage and thereafter; falls to itsquiescent value and, therefore, a positive voltage pulse is generatedacross cathode resistor '76, which pulse is transmitted over conductor77. ,The pulse-is then amplified in amplifier anda positive pulse outputis transmitted over conductor 81 to the nextcircuit stage, namely, topulse shaper 82, which merely provides a-pulse of the proper waveformfor operation of theMpulse circuitry. .The pulse which is still apositive voltage pulse, is next transmitted to the bi-stablemultivibrator 83 over the conductor 84 leading to the first stage of themultivibrator;

The pulse generating circuit has been considered up to this point asoperable solely by photocell tube 34. We will next consider the secondphotocell tube 33 and trace the pulses generated thereby.

The second photocell tube 33 is connected to a potentiometer circuitcomprising resistors 85, 86 and 87 similar to the one'previouslydiscussed. When the photocell tube is energizedas by a slit in thegrating traversing the light beam from source 31, a voltage is appliedto grid 90 of tube 91, thereby causing the tube to conduct. As furthercarriage travel carries the grating so that the slit is moved outof thelight beam and the opaque background of the grating. interrupts the beamto deenergize the photocell tube, the voltage which was applied to grid90 is removed and tube 91 is extinguished. Consequently, the voltage atcathode-92 was first raised and restored to its normal value, therebyresulting in a positive pulse being generated across cathode resistor 93and transmitted over conductor 94. The pulse is amplified in amplifier95 and then transmitted to the pulse shaper 96 over conductor 97, afterwhich it is transmitted to the second stage of the bi-stablemultivibrator 83 over conductor 98.

Because of the staggered arrangement of slits in the pair of associatedrows (Fig. 5), the pulses generated by the two photocells followoneanother alternately from each photocell. The pulses generated by onephotocell tube e.g. 34, trigger the bi stable multivibrator so that, forexample, the first tube therein produces an output pulse, whereas'thepulses generated'by the other photocell tube i.e. 33, trigger themultivibrator so that the second tube therein produces an output pulse.Inasmuch as the nurses generat d alternately-by the we photocell tubesare transmitted to the twoin'puts to a bi-stable rhulfi vibrator it, isclear that if two pulses'in succession or a'' series 'o'fjpulses aretransmitted to "one-input to the multivibrator, without theinterposition of a pulse to the s'ec-" ondxr'nultivibratorinput, onlythe first, such pulse is counte'df lt is the rnultivibrator, however,which insures that the generated pulses come alternately from the twophotocell tubes. This feature has been found extremely desirableparticularly underthe circumstances previously willfae transmitted tothe e t eae-"fonowei and from it re the counter." This" l'attef group ofcircuitsis thus seen outlined, but repeated here for; the sake ofclarity. If we consider interruption of thec'ar'riage motion during thephotographing of a line er characters, as when such motiontesrrested topermit changing the character font, andconsequently changethetypeface ofthe characters thereafter photographed, it has been discoveredthat thecarriage vibrates very slightly-in a direction'parallel to theguiderods-supporting the carriage and along which the carriage travels.Assume that the relative positionof the grating; and the photocell unitwhen these vibrations o'ccur-is such that'the light beamitself isrepeatedly interruptcd by the opaque background'of the grating andtransmitted by the slit, as would'occur if the arresting action takesplace when the boundarybetween a grating slit and 1 the opaquebackground is proximate to the light beam.

- pulsing ofthe photocell, when the carriage is being brought to a. stopand vibrates at the boundary between a 'slit and the grating background,will introduce a false to'be a dividing circuit wherein, the diyi's'oris'two.

' The utility of the foregoing arrangement is apparent y when oneconsiders that the lineardimensions' of the typographical em ofdiiferentpoint sizes are proportional to the point sizes. Thus the width of a 10point em is twice the width of a 5 point ern, and a unit of a point emis" twice the dimension of a unitof a 5 point ern. Therefore, if agratingis prepared and the slit'disposition is such that a pulse isgenerated for each unit vof a 5 point em traversed by the grating, theexact pulse count will measure the travel of the grating in terms of 5point-ems. How ev'er,-if as in the circuit hereinabovedescribed, everysecond pulse generated by the grating is counted, then the same row ofslits asis provided when recording 5 point character images may be usedwhen recording, 10 point character images. Asa further example,- if aslit arrangement is such that a pulse is generatedfor every unit of a 5/2 pointem, then by counting every second'pulse, the

same slit arrangement can be used for an 11 point cm.

In the embodiment disclosed, the grating isprovided with slitarrangements for measuring'grating '(i.e. car

countto'the counting device: As waslhereinabove rrientioned,--the' countcontrols thephotog'raphing of the' individual characters, "so it will beappreciated that a false countiwill' result: in an improperlyphotographed line.

Again pick-ing'up the aths that the pulses follow, the diagram (Fig. 12)shows that the output pulses from r'nultivibrator '83 are transmittedover conductors 100' and 101 to-the rn'ixercircuit102 which combines thetwo independent pulse trains into a single pulse train, the pulses ofwhich are transmitted as positive pulses to'conductor 103. Fromconductor I03, thepulses' ma travel over condii'ctor 104'throughnormally engaged contacts 105 to the counter-106. When the-pulses travelover this circuit each puls'e will be counted. Analte'rnative circuitpath is'frorn conductor-103 through normally separated contacts 107,amplifier 1 10, bi'-st'ablc niultivibrator 11 1, cathode follo'v've'r112"and ncrmallys'eparated contacts 113,to counter 1061' The" contacts105, 1 07-and 113 are actuated by i-nes'ameren eei1 (not shown)" sothatthe pulses are transmittedfrom coriander- 103 through either one of, the

two circuits disclosed-L The functioningofthe relay coiltocontroloperation of contacts is controlled in accordance with the point' sizeof the-charact'er images being recorded on the sensitized sheet? Thusforeman point'-'sizes,-e-.'g. 5, 5 /2, 6, 7, 8 and 9' points; therelayeoil will remain deenergized so that contacts -105 'stay in theirnormally engaged condition, while contacts 107 and 113 are separated.Therefore, all pulses generated by the photocell unit will be transslitin-another' pair ofrows, and that those for the larger mitted to thecounter." On the other hand, whenlarge point size images are beingrecorded, e.g. those of 10, 1'1, 12, 14; 16 and 18 po'intsjthe' relaycoil-will be energized and contacts 107 and 113' will be engaged andcontacts IQSsepai-ated. In thisinstance, the'puls'es will be transmittedthrough'arnplifier 1 10; bi-stable rnultivibrator 111 andcathodefollower 1'12'to'counter 106. For every two pulses transmitted ton'iultivibrator 111"; only one pulse riage') travel in unitsof a fiveand a ten point em, a 5 /2 and an 11 pointer'n, a 6- anda 12 point em,a7 and a 14 point ern, an 8 and 1 6 point em, and a 9 and an 18 pointem.- Thus, the machine can record character images of 12 different pointsizes'and yet it isrequired that the grat ing be provided as if it wereto beusedonly for 6 different point sizes.

sizes may be used.

'Oneof the chief advantages of such-a feature is that the.

size (area-wise, that is) lot the'gr'at-ing can be reduced'ap- Ofcourse, other combinations of point proximately to one-half of the sizethat would be required should a separate row, or pair of rows, of slitsbe provided for each point size. This permits flatness tolerances whichare imposed on thegrating surfaceto be more readily achieved;

A further examination of Fig. 2 will reveal that the first slit in apair of rows is'offset from the corresponding point sizes are olfsetthefarthest when considering the rightward'edge of the grating as areference. The reason for the offset is foundin" the arrangement ofthechar acters on the font plate and the relative location ofthe fontplateand the machine optical system. Incopending applicatiorijserial No;432,757; filed May 27, 1954, the

font plate is disclosed as having a plurality of em; squares disposedthereon, in each of which the particular character found therein, islocated by'two reference lines, one to vertically locate the characterand the other to hori- ,zontally locate thecharacter'as by'coincidingwith the leading or rightmost edge of the character. The optical systemis such (see copending application Serial No; 354,826, filed May 11,1953) and the fontplate isso located with respect thereto thatthe-optical center of the system passes through the midpoint. of each emsquare. The degree'otfset-for the various rows ofslits'on the grating isequal to one-half the difierence in the Width ofthe em squares for thetwo point sizes for which the rows are provided. Forexample, if'weconsider the rows of slits-for 6' point and 8 point images, the row for8 pointswill be offset a or 1 point. As a further example, if weconsider the 8 blum i l be maintained regardless of the point sizevimages which may be recorded in the lines of the column.

From the foregoing disclosure it is clear that the row of slits for 6points will be offset from the row of slits for 12 points. But, it willbe recalled that the present machine utilizes the same row of slits forboth 6 and 12 point recorded images. Consequently, there can be nophysical ofiset on the grating as there is for the point sizes havingdifferent rows. The offset must, however, be provided and it is providedby means of circuitry disclosed in copending application Serial No.696,448 filed simultaneously herewith. Sufiice it to say, for thepresent, that when photographing the smaller point sizes, e.g. 6 point,the first nine pulses generated (one-half the number of units of thetypographical em which contains 18 units in the present system) arediscarded. The same is true when recording any of the other smallerpoint sizes, that is, the first nine pulses generated by the grating arediscarded. If a system based on a twelve unit em is employed, the firstsix pulses will be omitted.

It is contemplated that many changes could be made to the preferredembodiment of this invention as above described without departing fromthe spirit and scope thereof, and therefore it is intended that allmatter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

Reference is made to copending application Serial No. 696,419 filedsimultaneously herewith in the name of Grube, which discloses and claimselectrical means for transmitting to the counter each successive pulseof the photocell unit or every other pulse thereof according to thepoint size of the character images being composed, in the manner and forthe purpose hereinabove described. So far as the present invention isconcerned, the successive pulses of the photocell unit could betransmitted directly to the counter 106 by the conductor 103, whichmeans that the elements 104, 105, 107, 110, 111, 112 and 113 could beomitted. The Grube circuitry has been shown herein as representing thebest mode of practicing the present invention.

What is claimed is:

1. In a phototypographical machine in which there is a relative linecomposing movement between the sensitized surface on which the textmatter is photo-graphed and the means for projecting character images,each of said character images having a characteristic width which is amultiple of a unit space, said unit space being a me determined part ofa given typographical em and in which said line composing movement ismeasured to control the photographing of successive character images,the combination of an opaque grating partaking of the line composingmovement and having a series of successively acting translucent slitsspaced apart at a distance proportional to the aforesaid unit space, twophotocells arranged at one side of the grating, two corresponding lightsources arranged at the opposite side of the grating, one of saidphotocells and its light source being arranged to cooperate with onlyevery other slit in the series, and the other of said photocells and itslight source being arranged to cooperate with only the intermediateslits in the series, whereby the two photocells are activatedalternately during the line composing movement of the grating by thealternate flashing and interruption of their respective light sources,and an electrical circuit energized by said photocells and controllingthe photographic action in accordance with unit variations in set widthsof the character images successively composed.

2. The combination according to claim 1, wherein the series oftranslucent slits are arranged in two rows, one row cooperating onlywith one photocell and its corresponding light source, and the secondrow cooperating only with the other photocell and its correspondinglight source, the slits in each row being spaced apart at a distanceproportional to two of the aforesaid unit spaces but staggered withreference to one another as between the rows, whereby the unit spacingof the slits throughout the series is preserved.

3. The combination according to claim 2, wherein the electrical circuitis capable of being energized by a single pulse only from eitherphotocell at a time.

4. The combination according to claim 2 wherein the electrical circuitincludes a bi-stable multivibrator with two inputs, one for eachphotocell, whereby the circuit can be energized only by successivepulses produced alternately by the two photocells.

5. The combination according to claim 2 wherein the typographical emtherein referred to is that based on the point size of the imagesrecorded on the sensitized surface.

6. The combination according to claim 2 wherein the grating is providedwith a plurality of series of translucent slits, the spacing of saidslits varying in the different series to accord with typographical emsbased on different point sizes.

7. The combination according to claim 2 wherein the electrical circuitwhich controls the photographic action includes an electric counter inwhich the unit set width value of each character image composed ispreviously registered.

8. In a phototypographical machine in which there is a relative linecomposing movement between the sensitized surface on which the textmatter is photographed and the means for projecting character images,each of said character images having a characteristic width which is amultiple of a unit space, said unit space being a predetermined part ofa given typographical em and in which said line composing movement ismeasured to control the photographing of successive character images,the combination of an electrical circuit for controlling thephotographic action in accordance with unit variations in set widths ofthe character images successively composed, a photocell unit for pulsingsaid circuit during the line composing movement for each unit space of agiven typographical em, and means for preventing the electrical circuitfrom being pulsed by the photocell unit more than once at a time foreach different unit space, said preventing means comprising a bi-stablemultivibrator with two inputs, one for every other pulse produced by thephotocell unit, and the other for the intermediate pulses produced bysaid photocell unit, whereby the circuit may be energized only bysuccessive pulses produced alternately by the photocell unit.

Turrettini Mar. 4, 1947 Hooven Aug. 9, 1955

